urinary system part 1

Urinary System:-
The urinary system consists of the paired kidney, ureters, bladder, and urethra this system contributes of the maintenance at homeostasis by a complex process that involves filtration,active absorption passive absorption, and: secretion . the result is the production of urine in which various metabolic waste products are eliminated.
Urine produced in the kidneys passes through the to the bladder .where it is temporarily stored and then released of the exterior through the urethra the tow kidneys produce about 125 ml of filtrate per minute of this amount. 124 ml is absorbed in the organ, and only 1 ml is released into the urelers as urine.
Kidney: cortex and pyramidal
The kidney is subdivided and outer region,the cortex and an inner region, the medulla. externally ,the cortex is covered with connective tissue capsule in the cortex the convoluted tubules glomeruli, straight tubules and medullary rays, are found, the cortex also contain renal corpuscles (glomerular or bowman capsule and glomeruli), the glomerulus is a tuft of capillaries formed from the afferent glomerular arterioles and supported by fine connective tissue.
The visceral layer of the glomerular capsule consists of modified epithelial cells called the podocytes, these cells closely follow the contours of the glomerulus and invest the capillary tuft. At the vascular pole the visceral epithelium reflects to become the parietal layer of the glornerular capsules. the space between the visceral layer and the parietal layer of the capsule is the capsular space,which become continuous with the lumen of proximal convoluted tubule at the urinary pole Numerous tubules sectioned in various planes, lie adjacent to the renal corpuscles the tubules are primarily of two types the proximal convoluted and distal convoluted, these tubules are the initial and terminal segments of nephron, respectively. the proximal convoluted tubules are numerous in the cortex, exhibit a small ,irregular lumen,and contain a single layer of large cuboidal cells with intensely eosinophilic mgranular cytoplasm the well— developed brush borders are present but are not always well preserved in sections.
Distal convoluted tubules are fewer in number and-exhibit a larger lumen with smaller ,cuboidal cells. The cytoplasm stanis less intensely and the brush borders are not present also the number of these cells are more than those in prximal tubules.
The medulla:
The medulla contain only straight portion of tubules and thin segments of loop of Henle. Illustrated in the outer medullary region are thin segments of loops of Henle lined with squamous epithelium straight segments of-distal tubules(ascending have simple cuboidal ep.) and straight segments of proximal tubule (descensing have simple cuboidal ep.) and collecting-tubules, in medulla contain the terminal portions of the collecting tubules, the papillary ducts ,these ducts have large diameters and wide lumina and are lined by tall, pale— staining columnar cells.